Continuum (1.3 mm) and J = 2 − 1 ¹³CO, C¹⁸O, and C¹⁷O line emission towards GLMP 953. Left: Maps of the continuum (colour map) and high-velocity line emission (contours). The continuum peak is at $\alpha ={19}^{\text{h}}{50}^{\text{m}}08\stackrel{\text{s}}{.}203$ and $\delta =+{25}^{°}11\prime 57\stackrel{″}{.}136$. The full lines show emission in the ¹³CO J = 2 − 1 integrated over the spectral intervals marked in grey line plot. Magenta and cyan contours mark red-shifted and blue-shifted emission, respectively, at 10%, 30%, 50%, and 70% of the peak values of 0.009 (red-shifted) and 0.007 (blue-shifted) Jy beam⁻¹ × km s⁻¹. Middle: Spectra of the ¹³CO J = 2 − 1, C¹⁸O J = 2 − 1, and C¹⁷O J = 2 − 1 lines. Right: Single-beam spectrum (to maximise the S/N of the weak emission) of the ¹³CO J = 2 − 1 line towards the continuum peak of GLMP 953 including a broader velocity range.